The present invention relates to a microactuator that may be used to actuate, for example, a suspension. Without limitation, the microactuator may be used in a disc drive suspension. More particularly, the present invention relates to a high resolution positioning mechanism having a co-located piezoelectric element and related lever assembly for moving a component connected to the lever assembly, such as moving a slider with respect to a rotatable disc.
Disc drives are well known in the magnetic storage industry. Disc drives are used to store digital information on rigid discs in a plurality of circular, concentric data tracks. Discs are mounted on a spindle motor that rotates the discs for operation. Information is read from or written to the disc surface via transducers carried on a slider supported relative to the disc surface via a suspension system.
Typically, the suspension assembly includes a load beam and a gimbal for supporting the slider. The slider is coupled to the gimbal at an upper surface of the slider. The gimbal is also coupled to the load beam. The lower surface of the slider defines an air-bearing surface. Rotation of a disc via the spindle motor interacts with the air-bearing surface of the slider to create a hydro-dynamic lifting force to lift the slider to fly above the disc surface for reading information from and writing information to the disc surface. The gimbal sheet supports the slider to allow the slider to pitch and roll relative to the disc surface for operation.
The load beam supplies a pre-load force to counteract the hydro-dynamic lifting force of the slider. The pre-load force supplied by the load beam and the hydro-dynamic lifting force created by the air-bearing surface and rotation of the disc define the flying characteristics of the slider (and transducers) above the disc surface.
Radial spacing between concentric data tracks on magnetic discs continues to decrease, requiring greater precision in head positioning. Conventionally, head positioning is accomplished by operating an actuator arm, which is attached to the suspension assembly, with a large-scale actuator motor, such as a voice coil motor. The large-scale motor lacks sufficient resolution to effectively accommodate high track density discs. Thus, a high-resolution head positioning mechanism is necessary to accommodate the more densely spaced tracks.
One design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional low resolution actuator motor, thereby effecting head positioning through dual stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning, including electromagnetic microactuators and more recently, piezoelectric micromotors. Use of a piezoelectric material as the microactuator appears quite promising, however, current implementations have shortcomings that limit the effectiveness of the microactuator.
For example, where the piezoelectric micromotor was offset from the slider, such as where the micromotor was implemented at the baseplate (where the actuator arm connects to the head suspension load beam), high forces were required from the microactuator to move the mass associated with the head suspension at a frequency high enough to support the bandwidth necessary for a given areal density. If the force was not great enough, the microactuator operated with lower natural frequency than was desirable, and the system could not support the bandwidth required. When the microactuator was co-located to the slider (where the microactuator is in direct contact or very close contact with the slider), such as where the microactuator was implemented directly on the slider, in one embodiment the complexity of slider design was increased and noise generated by the microactuator and by signal paths to it was induced into the head. New fabrication techniques had to be developed to integrate the slider and microactuator into a single structure. Therefore, the prior designs did not present ideal microactuator solutions.
There is a need in the art for a simple microactuator design to provide efficient high resolution head positioning in a dual-stage actuation system that can be implemented by readily available manufacturing processes.